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// Copyright (c) 2014, The Monero Project
//
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without modification, are
// permitted provided that the following conditions are met:
//
// 1. Redistributions of source code must retain the above copyright notice, this list of
// conditions and the following disclaimer.
//
// 2. Redistributions in binary form must reproduce the above copyright notice, this list
// of conditions and the following disclaimer in the documentation and/or other
// materials provided with the distribution.
//
// 3. Neither the name of the copyright holder nor the names of its contributors may be
// used to endorse or promote products derived from this software without specific
// prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
// MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
// THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
// STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
// THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
/*
* This file and its header file are for translating Electrum-style word lists
* into their equivalent byte representations for cross-compatibility with
* that method of "backing up" one's wallet keys.
*/
#include <string>
#include <cassert>
#include <map>
#include <cstdint>
#include <vector>
#include <boost/algorithm/string.hpp>
#include "crypto/crypto.h" // for declaration of crypto::secret_key
#include "mnemonics/electrum-words.h"
namespace crypto
{
namespace ElectrumWords
{
/* convert words to bytes, 3 words -> 4 bytes
* returns:
* false if not a multiple of 3 words, or if a words is not in the
* words list
*
* true otherwise
*/
bool words_to_bytes(const std::string& words, crypto::secret_key& dst)
{
int n = NUMWORDS; // hardcoded because this is what electrum uses
std::vector<std::string> wlist;
boost::split(wlist, words, boost::is_any_of(" "));
// error on non-compliant word list
if (wlist.size() != 12 && wlist.size() != 24) return false;
for (unsigned int i=0; i < wlist.size() / 3; i++)
{
uint32_t val;
uint32_t w1, w2, w3;
// verify all three words exist in the word list
if (wordsMap.count(wlist[i*3]) == 0 ||
wordsMap.count(wlist[i*3 + 1]) == 0 ||
wordsMap.count(wlist[i*3 + 2]) == 0)
{
return false;
}
w1 = wordsMap.at(wlist[i*3]);
w2 = wordsMap.at(wlist[i*3 + 1]);
w3 = wordsMap.at(wlist[i*3 + 2]);
val = w1 + n * (((n - w1) + w2) % n) + n * n * (((n - w2) + w3) % n);
if (!(val % n == w1)) return false;
memcpy(dst.data + i * 4, &val, 4); // copy 4 bytes to position
}
std::string wlist_copy = words;
if (wlist.size() == 12)
{
memcpy(dst.data, dst.data + 16, 16); // if electrum 12-word seed, duplicate
wlist_copy += ' ';
wlist_copy += words;
}
return true;
}
/* convert bytes to words, 4 bytes-> 3 words
* returns:
* false if wrong number of bytes (shouldn't be possible)
* true otherwise
*/
bool bytes_to_words(const crypto::secret_key& src, std::string& words)
{
int n = NUMWORDS; // hardcoded because this is what electrum uses
if (sizeof(src.data) % 4 != 0) return false;
// 8 bytes -> 3 words. 8 digits base 16 -> 3 digits base 1626
for (unsigned int i=0; i < sizeof(src.data)/4; i++, words += ' ')
{
uint32_t w1, w2, w3;
uint32_t val;
memcpy(&val, (src.data) + (i * 4), 4);
w1 = val % n;
w2 = ((val / n) + w1) % n;
w3 = (((val / n) / n) + w2) % n;
words += wordsArray[w1];
words += ' ';
words += wordsArray[w2];
words += ' ';
words += wordsArray[w3];
}
return false;
}
} // namespace ElectrumWords
} // namespace crypto
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